I was pulling a lite wieght trailer had just come off a big hill with no problems, when all of a sudden I lost power, in fact dropped to about 50 mph top speed while pulling the trailer and not much different with no trailer. I repalce the pick up pump thinking it might bd a fuel delivery problem and also the turbo relay. I have a "new engine with only 25,000 miles on it and a new injection pump. I also use a fuel conditioner. Before I started the trip the truck stalled a couple time but always restarted. Now when I get it started which is a real hard start I get a huge black cloud outa the exhaust .... "unburnt fuel"? I'm thinking the PMD is gone but not to sure anybody got any ideas.